56 Scientific Intelligence. 



13. Method of proof of the law of radiation of an absolutely 

 dark body. — W. Wien and O. Lummee, who had apparently been 

 working independently upon the problem upon which St. John 

 was also working (Ann. der Physik und Chemie, No. 11, 1895, p. 

 433), state the conditions which should be fulfilled in making 

 observations according to Kirchhoff's law, and for the measure of 

 radiation according to Stefan's law. They suggest that two pieces 

 of thin platinum foil brought to incandescence by an electric cur- 

 rent be placed near each other. One is provided with a 

 slit through which the other is viewed. The inner appears much 

 brighter than the outer. The temperature can be determined by 

 the increase of resistance of the platinum. The arrangement can 

 be used also as a bolometer, the radiation to be measured being 

 sent through the slit and both pieces of platinum foil thus heated. 

 In this way a result is obtained which is independent of the indi- 

 vidual peculiarities of the absorbing and emitting surfaces, and 

 the absolute radiation can be measured more correctly than by 

 previous methods. — Ann. der Physik und Chemie, No. 11, 1895, 

 pp. 451-456. j. t. 



14. Plasticity of Ice, by O. Mugge. — In corroboration of the 

 results of McConnell (Proc. Roy. Soc, xlviii, p. 259, 1890; and 

 xlix, p. 323, 1891), experiments are made upon the bending of 

 small bars of ice, held horizontally, supported at the ends, and 

 loaded at the middle. If such a bar, or crystal, is so cut that the 

 optical axis is perpendicular to the length, the load causes consid- 

 erable bending ; but a rod having the optical axis horizontal shows 

 no appreciable bending under these conditions. This agrees with 

 the supposition that the crystals consist of thin laminae, formed 

 of a flexible but almost inextensible substance, the interspaces 

 being filled with a separating medium which is sufficiently viscous 

 to retard the mutual gliding of the plates. Ice, in this respect, 

 resembles KMnCl 3 . 2aq., where the deformation results, similarly, 

 from a motion of translation of the component laminae, retarded 

 by viscous matter in the interspaces, The experiments seem to 

 show that this motion of translation takes place with equal facil- 

 ity in all directions parallel to the end surfaces ; and, within the 

 limits of — 3° C. and — 16° C, the extent of the motion, for a 

 given load, appears to be independent of temperature. (Nach. 

 G. Wiss. Gottingen, pp. 173-174, 1895.)— Phys. Soc. Abstracts, 

 Nov., 1895. 



15. Ueber den Magnetismus der Planeten vo?i Ernst Leyst. 

 118 pp. 4to. St. Petersburg, 1894. (Repertorium der Meteorolo- 

 gie herausgegeben von der K. Akad. der Wissenschaften.) — The 

 author has exhaustively examined the photographic records of the 

 magnetographs at St. Petersburg, and later at Pawlowsk between 

 1873 and 1889, to see if it is possible to trace any systematic effect 

 produced on the terrestrial magnetic elements by the other 

 planets of the solar system. In this paper the author deals at 

 great length with the declination records, and somewhat less 

 fully with those of horizontal force. Three methods are em- 



